1. Field of the Invention
The present invention relates to a single-plate dual-band antenna, and more particularly, to an integrally formed, resilient, single-plate dual-band antenna for use with a wireless network device, and a wireless network device having such antenna.
2. Description of the Prior Art
FIG. 1 is a perspective view of a conventional wireless network device 10 of a wireless network card, for example. The wireless network device 10 usually includes a main body 11, an internal circuit device 12 located inside the main body 11, a connector portion 13 located at one end of the main body 11 for connecting an external mainframe (not shown), and an antenna signal receiving/transmitting portion 14 located at another end of the main body 11 opposing the connector portion 13. Generally, the antenna signal receiving/transmitting portion 14 is provided with a housing that is made of a non-metal material. When the wireless network device 10 is connected to the external mainframe, the antenna signal receiving/transmitting portion 14 must be exposed outside of the external mainframe so as to effectively receive and transmit wireless signals.
FIG. 2 is a schematic view of a conventional internal circuit device 20 of wireless network device. The conventional internal circuit device 20 of the wireless network device includes a substrate 21, a control circuit 22 located on the substrate 21, a ground portion 23 covering a predetermined area of the substrate 21, and an antenna unit 24 electrically connected to the control circuit 22. The conventional antenna unit 24, as illustrated in FIG. 2, includes a first antenna 241 and a second antenna 242 located at two lateral sides of the substrate 21, respectively. Since the antenna unit of this conventional internal circuit device 20 is designed as printed monopole antenna printed on the substrate 21. Due to limitation in height difference along a vertical direction, this type of printed antenna can achieve a better radiation pattern and higher gain on an X-Y plane (horizontal plane) only by designing different shapes of the first antenna 241 and the second antenna 242; but there is almost no further improvement of antenna gain along the vertical Z direction. However, the design of current wireless network device tends to be a vertical stand type, so as to reduce the space occupied by the wireless network device, as well as to make the appearance of the wireless network device more modern and high-tech. It is obvious that the conventional printed antenna cannot meet the requirement for the vertical stand type wireless network device due to the poor gain along the vertical Z direction.
FIG. 3 is a chart showing a radiation pattern measured on an X-Y plane of the first antenna of the conventional printed antenna unit 24 as shown in FIG. 2. From the radiation pattern of FIG. 3, it can be seen that the peak gain value of the first antenna 241 along the vertical direction is only −15.89 dBi, which is apparently lower than the minimum standard acceptable by consumers (a general requirement is that the gain value should be at least higher than −10 dBi). Thus, there are still rooms for improvement regarding to the design of antenna, which is also critically important for meeting consumer's need for high performance antenna.